Temporal reprogramming of calcium signalling via crosstalk of gonadotrophin receptors that associate as functionally asymmetric heteromers

K C Jonas,J Mora,M Virta,S Franks,A C Hanyaloglu,S Chen,I Huhtaniemi

doi:10.1038/s41598-018-20722-5

K C Jonas, J Mora + Show 5 more

Open Access

https://doi.org/10.1038/s41598-018-20722-5

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Journal: Scientific Reports	Publication Date: Feb 2, 2018
Citations: 47	License type: open-access

Affiliation: Imperial College London, Roche (Switzerland)

Abstract

Signal crosstalk between distinct G protein-coupled receptors (GPCRs) is one mechanism that underlies pleiotropic signalling. Such crosstalk is also pertinent for GPCRs activated by gonadotrophic hormones; follicle-stimulating hormone (FSH) and luteinising hormone (LH), with specific relevance to female reproduction. Here, we demonstrate that gonadotrophin receptor crosstalk alters LH-induced Gαq/11-calcium profiles. LH-induced calcium signals in both heterologous and primary human granulosa cells were prolonged by FSHR coexpression via influx of extracellular calcium in a receptor specific manner. LHR/FSHR crosstalk involves Gαq/11 activation as a Gαq/11 inhibitor abolished calcium responses. Interestingly, the enhanced LH-mediated calcium signalling induced by FSHR co-expression was dependent on intracellular calcium store release and involved Gβγ. Biophysical analysis of receptor and Gαq interactions indicated that ligand-dependent association between LHR and Gαq was rearranged in the presence of FSHR, enabling FSHR to closely associate with Gαq following LHR activation. This suggests that crosstalk may occur via close associations as heteromers. Super-resolution imaging revealed that LHR and FSHR formed constitutive heteromers at the plasma membrane. Intriguingly, the ratio of LHR:FSHR in heterotetramers was specifically altered following LH treatment. We propose that functionally significant FSHR/LHR crosstalk reprograms LH-mediated calcium signalling at the interface of receptor-G protein via formation of asymmetric complexes.

Highlights

How individual cells integrate and decode multiple signals from an array of distinct receptors is a fundamental question in cell biology
It is established that one of the key physiological G protein pathways activated by luteinising hormone (LH)/luteinising hormone receptor (LHR), but not by follicle-stimulating hormone (FSH)/follicle-stimulating hormone receptor (FSHR), is Gαq/11, leading to activation of PLC and increase in inositol phosphates and intracellular Ca2+ 14,15
Crosstalk is highly pertinent for the G protein-coupled receptors (GPCRs) playing multiple key roles in both reproduction and pregnancy, which includes the gonadotrophin hormone receptors LHR and FSHR

Summary

Introduction

How individual cells integrate and decode multiple signals from an array of distinct receptors is a fundamental question in cell biology. One mechanism contributing to this pleiotropy in cell signalling is crosstalk of GPCR signalling, and that such crosstalk can occur via GPCR heteromerisation The latter is defined as a complex of at least two different receptor protomers, with distinct biochemical properties from its individual components or homomers[5]. LHR/FSHR crosstalk has been shown to negatively cross-modulate Gαs-cAMP signalling[20] This inhibition of the primary G protein-signalling pathway by each receptor raises an interesting question in how such crosstalk may impact Gαq/11 signalling that is key to follicular function. Employing biophysical and super-resolution technologies, we demonstrate that LHR and FSHR form functional asymmetric complexes with Gαq, and that these receptors form distinct ligand-dependent heterotetrameric profiles

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